July 7, 1550 is the traditional date chocolate is thought to have been introduced to Europe. An excerpt from the article:
"Holiday makers are constantly on the hunt for a reason to munch on chocolate, so the calendar offers plenty of excuses to buy a bar. July 7 is also Chocolate Day, a nod to the historical tradition that the day marks when chocolate was first brought to Europe on July 7, 1550, though a number of sources argue that it might have hit the continent’s shores as far back as 1504, thanks to Christopher Columbus. Official day or not, we do know that chocolate first arrived in Europe some time in the 16th century. There's also National Milk Chocolate Day on July 28, International Chocolate Day on September 13, and, of course, National Bittersweet Chocolate With Almonds Day on November 7."